fringing pattern

[Ralf Kohley]

Posted to CCD-world:
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Hello CCD-world,

I have a question which is bothering me already for some time and since I have
only little experience on this subject, I would like to hear your advice.
The well known problem of interference fringing in thinned CCDs is especially
harzardous when using these CCDs in spectrographs. Therefore, I would like
to know, how you people out there deal with this problem. Any kind of remarks (to
the following questions) are very welcome:

1)  What causes the real trouble when trying to get rid of the fringing pattern?
     (I believe it is the fringing amplitude, but something else??? Unstable patterns
     due to rotation, vibration or flexures of the instrument?)

2)  Which are the measures to reduce the fringing amplitude or to shift the set-in
     wavelength more to the near-IR end?

3)  Are there any special techniques beside flat-fielding to try to remove the pattern?

Best wishes,

     Ralf
  
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Ralf Kohley                             e-mail:   rkohley at ll.iac.es
GTC Project GRANTECAN, S.A. (IAC)       phone:    +34 922 315 353 
c/ Vía Láctea s/n                       fax:      +34 922 315 032
38200 LA LAGUNA (Tenerife), SPAIN       web:      http://www.gtc.iac.es
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